Show me an "edgy", "risque" or "good-girl-gone-bad" pop star and I will show you her tongue. From Azealia Banks' plum-licking appendage to Rihanna's palate quarter pounder, Kei$ha's oral runway to Iggy Azalea's Spam-like protrusion, a public display of tongue is the front-cover pop version of the middle finger.

It's rude, but not actually offensive. It's provocative, without being explicit. It's masturbation, under the guise of mastication.

Which made Ma Cyrus's copycat oral gurning, to a horde of panting photographers last week, just a little uncomfortable. Particularly when, that same week, Miley joked that the reason for her constant tonguing was: "I'm having tiny strokes, yo!"

Nicki Minaj on the cover of Complex 10. Photograph: Complex 10

That's right. I'm talking about Miley Cyrus's tongue: an appendage with so much coverage that it probably has its own booking agent.

The prominence of the female tongue in pop is hardly new. Back in 1980, Mick Rock photographed a 22-year-old Madonna, provocatively lapping at her own shoulder. Cut to 28 years later and here's Madge again, airing her epiglottis in the video to 4 Minutes. Madonna has, in short, been waving her tongue around since Miley was just a twinkle in Billy Ray's trousers.

But what does this semi-seductive, faux-aggressive, part-provocative expression actually mean? Why do female pop stars keep baring their tongues? Well, the allusions to having a gum full of cocaine are certainly one element. The Marc Bolan, Iggy Pop, Mick Jagger rock legacy of an open orifice is another. And there are also, as anyone who's ever had the misfortune to flick through Terry Richardson's work can tell you, the yawn-worthy references to oral sex. But there is more at play here than just sex and drugs and rock'n'roll.

The tongue has long been our most basic barometer of medical health. In his 1871 introductory lecture to new medical students at King's College hospital, Sir Thomas Watson warned: "A patient would think you careless, or ignorant of your craft, if you did not, at every visit, look at his tongue, as well as feel his pulse."

Britney Spears in 2003. Photograph: Scott Gries/Getty Images

On the other hand, unstoppable or uncontrollable tongue flailing has, for centuries, been interpreted as a sign of mental illness. Think of those terrifying 19th-century Eadweard Muybridge photographs of so-called "hysterics" chained to their beds, tongues lashing, eyes wide. Or the last howling, spit-flying throes of rabies victims and they sink into madness and death.

Perhaps a bared tongue is the ultimate challenge to be judged; an invitation to be diagnosed. Is this tongue a sign of health or hysteria? Is it provocative or problematic? Is this, in short, the tongue of an independent woman, or a howling maniac?

One of pop's other most famous tongue twisters was the woman known as Scary Spice. Melanie Brown licked, poked and waggled her pierced tongue all over the 1990s, in the presence of royalty and lads mags alike. A visible tonsil-tickler became – to 90s ladette culture – shorthand for "scary", "crazy" and "out of control" sexuality. Babes gone bonkers, if you will.

Miley Cyrus shows off 'the front-cover pop version of the middle finger' at the release party for her album Bangerz. Photograph: Jamie McCarthy/Getty Images

Across the pond, one of pop's most psychologically vulnerable stars, Britney Spears, used her Slave 4 U-era flashing, snake-like tongue to announce to the world that she had changed. Her childhood, her virginity and her taste for wearing co-ordinated denim ball gowns were well and truly gone. Modesty had been replaced with an open mouth. Likewise, Nicki Minaj – another pop star known for her supposed "madness" – was photographed for the cover of Complex in 2012, sticking out a vivid, black-and-white-striped tongue.

But, is a lolling, tooth-squeezed, erect or lapping tongue really the only way to announce to the media world that you've changed? Can female pop stars only prove their move into maturity by baring their oral appendage? Wouldn't it be more effective – stop me if this sounds crazy – to use that tongue to, I don't know, speak?

Wouldn't the music industry benefit more from a generation of young women giving the patriarchy a tongue-lashing, rather than simply baring their flaccid tongues?